Role of dietary proteins in intestinal glucose absorption

Abstract

Proteins constitute a source of nutrients widely consumed all over the world. Dietary proteins from animal or plant origin have been shown to play a beneficial role in glucose homeostasis by promoting the secretion of appetite regulating gut hormones such as CCK, peptide YY, and GLP-1. The objective of this study was to determine whether dietary proteins could regulate another aspect of intestinal glucose metabolism: the intestinal glucose absorption. To achieve this, the acute effect of different proteins on mRNA expression of transporters involved in the absorption of glucose, namely SGLT1 and GLUT2, was assessed using an in vivo and in vitro method. The inhibition of alpha-glucosidase is another way to control the glucose absorption. Thus, the effect of proteins on alpha-glucosidase activity was also assessed using an acellular model. The results obtained from the in vivo experiment have overall demonstrated a decrease trend of relative mRNA level of GLUT2 and, to a lesser extent, SGLT1 mRNA level expression. Among the proteins tested (fish gelatin, pea proteins, ovalbumin, bovine hemoglobin and casein), the ingestion of ovalbumin by rats have shown a significant decrease of GLUT2 relative mRNA expression level. Concerning the inhibition of alpha-glucosidase activity, it has been shown that some peptides could have a role as stimulator or inhibitor depending on their structure (linear or cyclic). Moreover, the inhibitory effect of hemoglobin could be comparable to acarbose which is used as a drug to treat diabetes. This work opened the field to promising prospects such as the identification of peptides that interact directly or indirectly with transporters as well as the identification of the hemoglobin-derived peptide that interacts with the enzyme.